Funds are requested to purchase equipment to be integrated into an Advanced Microscopy Facility for th use of ten NIH-funded investigators in the departments of Biology, Biophysics and Chemical Engineering on the Johns Hopkins University Homewood campus, as well as outside users. Advances in quantitative light microscopy now offer unprecedented insight into cell organization, the structural basis of cell function, cell signaling and macromolecular function. However, sophisticated equipment is required in order to benefit from this new technology. Many investigators on this campus who wish to employ these new techniques must currently borrow scarce free time on (sometimes quite distant) machines or, too often, must simply abandon hope of pursing such lines of research. The proposed facility is designed to meet the Major Users' current needs, while providing the flexibility to meet future needs, as well. Our design goals emphasize flexibility, user-friendliness, and networking. The facility will be supported by a combination of institutional support and user fees, and space capacity will be made available to other investigators both on and off the Homewood campus. Initially anticipated applications of this facility include studies of signal transduction, membrane biophysics, protein targeting, cytoskeletal organization, gap junction dynamics, axonogenesis, mitotic motors, cell locomotion and vesicular transport.